Machine for producing combined cross and covering seams



F. EBERT 2,140,693

MACHINE FOR PRODUCING COMBINED CROSS AND COVERING SEAMS Dec. 20, 1938.

Filed April 1, 1957 3 Sheets-Sheet 1 Fig.1.

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'F. EBERT Dec. 20, 1938.

.MACHINE FOR PRODUCING COMBINED CROSS AND COVERING SEAMS Filed April 1, 1937 3 Sheets-Sheet 2 F. EBERT Dec. 20, 1938.

MACHINE FOR PRODUCING COMBINED CROSS AND COVERING SEAMS Filed April 1, 1937 s SheetsShe et s throat plate portion.

Patented Dec. 20, 1938 UNITED STATES PATENT OFFICE MACHINl'l FOR PRODUCING COMBINED CROSS AND COVERING SEAMS Application April 1, 1937, SerialNo. 134,417 In Germany April 3, 1936 4 Claims.

throughgoing stitching of the other piece of material-and also the provision of a covering seam may be performed in one operation by needles operating vertically to the web of material. In this connection it has been found that the seam usually tends somewhat to pucker, as the piece of material is not guided in sufficiently reliable fashion. For the same reason the blind-stitching of the one piece of material is also irregular, and a seam of this nature is accompanied by certain difliculties particularly in the case of very th n materials.

These drawbacks are obviated according to the invention by the fact that the two pieces of material having the edges folded over obliquely to the web are fed to the needle at different heights, in such fashion that the piece of material to be blind-stitched is situated somewhat higher than the piece of material to be furnished with the throughgoing stitches. 'In this manner there is obtained a distinct fold at the edge of the higher piece of material through which the blind stitches pass, 'so that the blind-stitching is able to take place with greatest accuracy.

The present invention is an improvement over the mechanism of Patent No. 2,044,275, dated June 16, 1936.

Preferably there is employed for this method a sewing machine having an overhanging workcarrying arm and a throat plate constructed to swing out laterally, which throat-plate is arranged to a certain extent lower than the throat plate portion over which there is fed the other piece of material.

The presser foot capable of the lateral movement is preferably made to be adjustable, so that the difference in height upon the feeding of the material may be regulated dependent on the thickness of the material.

Above the throat plate there may be provided a guide bar, which maintains the material fed over the throat plate portion in contact with the latter, so that this web of material is introduced below the other web of material fed over the other This guide bar may then act at the same time as a lateral guide for the somewhat higher piece of material fed over the throat plate, and accordingly provide an exact limitation in respect of the folded edge, in this way also assisting to ensure proper blind-stitching.

The guide bar is preferably secured in shiftable and laterally adjustable fashion to a resilient side portion of the mainpresser foot, which portion is capable of swinging upwards. The spring force moving the guide bar downwards may also be made to be adjustable.

The laterally movable throat plate portion may also be furnished with an additional recess, over which there is arranged the .guide bar, so that the piece of material fed over the throat plate portion is pressed into this recess and is also introduced in reliable fashion below the other piece of material even in the event of transverse seams which serve to increase the thickness of the material. These transverse seams are then tightly pressed down, and a neatseam may be produced also at these points.

An embodiment of a sewing machine of the overhanging arm type for carrying out the method according to the invention is illustrated by way of example in the accompanying drawings. Fig. l is a front view of a part of the sewing machine showing the laterally swinging throat plate portion, the throat plate with the upper presser foot and the guide bar and the feed dog in the operative position.

Fig. 2 is an elevational viewof Fig. 1.

Fig. 3 is a plan view thereof.

Fig. 4 is a longitudinal section taken along the line A-A in Fig. 3, the parts not pertaining to the invention being omitted, but the pieces of material having been included.

Fig. 5 is a vertical section taken-along the line B-B in Fig. 3.

Fig. 6 is a partial front view of the parts with the pieces of material, and

Fig. 7 is a perspective view of the front end of the arm without the upper presser foot.

As disclosed more particularly by Figs. 5 and 6, the material m, in accordance with the invention, is fed at a somewhat lower level than the piece of material 11. For this purpose the throat plate portion a, which is capable of a swinging move-.- ment, is arrangedto be somewhat lower than the throat plate portion Z. As shown clearly in Figs. 5 and 6, the throat plate and,the presser foot are so constructed that the edges of the pieces of' material are folded over obliquely to the plane of the material, so that the material 11 is merely blind-stitched by the needle, while the stitches are taken completely through the piece of material m. The throat plate portion a is furnished with a recess 1 which may have a small slope (Figs. 4 and 7)., so that at this point the difference in height between the webs m and n is on the throat plate portion a, there is provided a guide bar 0, which is adjustably secured to the resilient side portion (1 by means of a screw e. The side portion itself is pivotally secured to the upper presser foot carrier g by a screw f. Below the side portion there is sufficient space to enable the material to, pass through without obstruction. This space is adjustable by means of a shiftable stop k. The resiliency of the side portion d is obtained by means of a spring i, the force of which is also adjustable, so that there may be regulated the pressure of the guide bar on the material The attachment of the guide bar 0 to the side portion d by means of the screw e is such that the bar is adjustable laterally, i. e., may be adjusted along the edge of the right hand piece of material at right angles to the direction of sewing. As shown particularly clearly in Fig, 4, this guide bar presses the material m against the laterally movable throat plate portion a and also into the recess 'or inclinedportion b, above which it is arranged.

Owing to the lateral adjustability of the guide bar 0 by means of the screw e it is accomplished that this guide bar, dependent on the thickness of the material, is capable of being approached to such extent towards the throat plate that an exact guiding is provided in respect of the folding of the piece of material 11, and that this foldingis in point of fact so exactly performed that proper blind-stitching of the material by the needle takes place. As clearly shown in the drawings the portion a is a part of the throat plate and this part a is so arranged that it can yield laterally, if the layers are thicker than the slot provided between the portions a and l of the throat plate.

The recess b offers particular advantage in those cases in which the material contains transverse seams, which are then compressed by the guide bar 0 and despite the greater thickness of the material are introduced in reliable fashion below the folded edge of the piece of material 12, so that the seam will be produced perfectly reliably and accurately also at these points.

It is accordingly important to feed the two pieces of material m and n at different heights,

terial is blind-stitched by the needle in accurate fashion.

The invention may naturally also be employed for any other kind of combined edge and covering scam, in particular both in the case of a method in which aneedle for producing fastening stitches operates in front of two or more covvering seam needles, as well as in an embodiment in which two or more needles act in alignment.

What I claim as new and desire to secure by Letters Patent is:

1. In a work-carrying arm sewing machine having a needle and a presser foot the combination of a throat-plate on the free end of the said arm and having a separate front portion arranged at a lower level than the adjacent front part of the throat-plate, the said separate front portion being pivotally mounted to be able to yield laterally;

2. In a work-carrying arm sewing machine having a needle anda presser foot the combination of a throat-plate on the free end of the said arm and having a separate front portion arranged at a lower level than the adjacent front portion of the throat-plate, the said separate front portion being pivotally mounted to be able to yield laterally, and an auxiliary presser foot on the said presser foot adapted to yield in an upward direction and provided with a guide bar, the said guide bar being adapted to be laterally adjusted to be able to accurately guide the fold or edge of the upper layer of material.

3. A structure according to claim. 2, in which the yieldable throat-plate portion is provided with an inclined part upon the surface of which the lower layer of material is pressed by the guide bar.

4. A structure according to claim '1, in which an auxiliary presser foot having a guide bar is provided, said auxiliary presser foot being on said presser foot and in which the yieldable throatplate portion is provided with an inclined part upon the surface of which the lower layer of material is pressed by the guide bar.

FRITZ EBERT. 

